What ho! A foe! I've discovered that AMD's high end processors actually benchmark HIGHER than Intel's through SPEC, which is certainly more reliable than that Futuremark crap! But hold on! Check out this: http://www.apple.com/powermac/performance/
...but back to the point. The Opteron clocked higher than the Xeon! In the end, P4 3.8 Ghz, along with the FX-57 and the Opteron, ruled the list... oh yea...here it is: http://www.spec.org/cpu2000/results/cpu2000.html
These are the most recent: http://www.spec.org/cpu2000/results/res2006q2/
Notice the capability of SunFire and SunUltra. Very impressive.